Use the ARM64 simulator on the experimental MSan bot.
Use the ARM64 simulator on the experimental MSan bot.

This allows MSan to instrument JS code.

BUG=354798
TBR=glider@chromium.org

Review URL: https://codereview.chromium.org/226363002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@261796 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build